Method of making internal wrenching tools



- INVENTOR. Lawrence Domaek L. C. DOMACK METHOD OF MAKING INTERNAL WRENCHING TOOLS Filed June 16, 1947 Dec. 28, 1948.

. 7ll/llllI/ll/ Patented Dec. 28, 1948 METHOD OF MAKING INTERNAL WRENCHING TOOLS Lawrence C. Domack, Elmwood Park, Ill.

Application June 16, 1947, Serial No. 754,858

Claims. (Cl. 76-114) This invention relates to a novel method of making an improved internal wrenching tool.

An important object in connection with the method of making the tool is a step of pressing a hardened bit into an initially-broachedbore in a. shank in such a manner that the bit actually performs a secondary broaching operation and seats itself positively in a force-fit manner into a reduced cross-section portion of the bore.

An important object in connection with the tool itself is the provision of means for removing and replacing the bit portion thereof in the event of breakage or excessive wear.

Other objects and advantages will be apparent from the following description taken in connection with the drawings in which: I

Figure l is a perspective view of one embodiment of the present invention illustrating, in broken lines, one form of driving member usable with it;

Fig. 2 is a longitudinal, sectional view of the composite tool shown in Fig. 1;

Fig. 3 is a top or plan view of Fig. 2;

Fig. 4 is a transverse, sectional view of Fig. 2, taken along the line 44 of Fig. 2; and

Figs. 5, 6, and '7 are longitudinal, sectional views of the shank portion of the tool, showing a preferred progression of steps in forming and assembling the tool.

Like parts are referred to by like reference characters throughout the figures.

Referring now more particularly to the embodiment shown in the drawings, the improved composite tool, generally designated l9, comprises a shank and a bit 24.

The shank 2D is formed with a polygonal socket 2| (square, in this case), preferably axially aligned with a minor socket or'bore, which is generally designated 22 (Fig. 2). The bore 22 has an exterior, non-circular or polygonal portion 23 (hexagonal, in this case) whichfri'ctionally grips the similarly non-circular bit 24, as the result of a pressed or driven fit to be described. The bore 22 also has an inner portion 25a of circular cross-section (see Fig. 3) which is preferably in communication with the socket 2|, as shown, in order to facilitate removal of the bit by a punch or other driving toolinserted through the open socket 2|.

The tool I 9 is designed to supplement a line of socket tools or fittings, so as to adapt a standard-sized, male-ended driver (such as the T- handled member designated 26 in Fig. 1) to the driving of a socketor recessed-head screw (not shown). Formerly, L-shaped, polygonal crosssection bars have been employed for this purpose, but they have been inconvenient to use, particularly where it is desired to spin the screw down rapidly prior to wrenching, as well as difiicult to use in applying high wrenching torques without using a pipe telescopically fitted over the end of the L member to increase its effective length. Many of such socket-head screws are provided with entirely smooth outer surfaces on their heads so they are slippery, especially when grasped by a wet or oily hand. Therefore, to further facilitate use of this improved tool, it is preferable that the outer cylindrical surface 21 be knurled, as shown, so it can be firmly grasped, and the screw at the end of the bit thereby quickly spun into place even with very oily, slippery hands. It will be understood that the T-handled driving member 26 is shown only by way of illustration, since the tool l9 can be readily adapted for use with other conventional male-end socket driving tools, such as ratchets, crank-type, high-speed wrenches, and the like. An important part of the present invention is the method by which the internal wrenching tool [9 is made so as to be economical, to hold the bit 24 firmly in place, and yet to permit the bit to be readily removable for replacement when necessary. 3

The final steps, with which this invention is concerned, in making the composite tool I9 are illustrated in Figs, 5, 6, 7, and 2. The shank 20 is first formed, as shown in Fig. 5, by appropriate forging, knurling, and machining operations. Next, as shown in Fig. 6, the circular bore 25 is formed, axially aligned with the socket 2|, preferably extending entirely through the shank. Then, by an appropriate initial broaching operation, an outer portion 28 of the bore 25 is enlarged to form a non-circular or polygonal crosssection, as shown in Fig. '7, an inner portion 25a of the bore remaining circular. In this case, the broached portion 28 is approximately the crosssection of the bit 24, but slightly smaller so that pressing the bit into place during the next operation causes a secondary breaching or enlargement of the bore. Preliminary to this next step, the leading end 3| of the bit is first formed so it will effect such breaching action when so pressed through the bore 25. For example, I have found, by simply cutting the leading end 3| off square, that the bit itself, if suitably treated to have a hardness suitably exceeding that of the shank, will function in the manner of a secondary broaching tool. In carrying out this punch down through the inner end of the bone;

22 and replacing with a new bit inthe manner above described, the new bit being -seatedffirmly in the circular cross-section portion of the bore with its end prefer-ably driven past; the locatiom of the previous bit.

While, in the embodiment shown; the bit; is- V illustrated as of symmetrically hexagonatcross-gv section frictionally gripped about its entire p riphery by. asimilarly hexagonalpontinuous seat formed in t'heshank, it will be app-arent,thatf other cross-sectionalshapes maybe-satisfactorily employed: E'or example, the-initial breaching-operation need'onlyhe effective to modify the cross sectionof" the bore so" that a. portion of it approximates, the shape of "only two or: more radial= 1y extended portions; (as; for; instance; apice in the case of'a pol'ygonal'cross-section) of thebit, said bore, portions being slightlyundersizedj radially with resp'ect'to-the'bit sothe latterwill ac tually cut' away or: displace .aportion thereof when thaparts-are pressed together-seas to form;

4 broached portion thereof to thereby enlarge the bore by a secondary broaching action of the bit on the bore to hold the bit firmly in place by frictional engagement. I

3. A method of joining .a socketed shank to a polygonal cross-section bit, to form an internal wrenching tool, comprising the steps of: (a) f -orming in said shank a bore open at both ends and-ialignediwitlnsaid spoke toiiacilitate the ins'e'rtion of' a punch" or other driving toolinto said here through said socket; (b) broaching a portion of said bore to a cross-section, corre- I spondingainr-s'hape but slightly smaller than said "polygonal bit; and (c) pressing an end portion otisaidrbitientirely through the broached ortion of said bore and into the unbroached portion thereon to cut awaythe interior of said bore to enlargetheflatter sufficiently to permit the bit to enter therein and be gripped by .a force fit.

two or more longitudinally extending;- circunrferentially spaced frictionarseats ,foritself irrthe shank; These circumferentially sp acedseats= will preferably be diametrioar when: only 'tW-o areprovided;

It is belieyed that in-view' of ft'h'e above d-escrip tion, ,both-asto structure-andfunct-i-on ofthe tool; the operation and use-of the t-(mlwillbe; obvious Althoughforthe -pur-pos e of illustrationi'haveshown and describedonly one form or my-i1n-' pr vedtool*an-dapreierredmethod-ofmakingfit, it-; will be apparent that many modifications maybe employed Without departing fromthe spirit/ and scope of -the invention; as indicated b'y'the appended claims;

I claim:

1 A- method of joiningasocketed shank to a non-circular cross-sectlon bit; to form an internalwrenching tool comprisingthe steps of? (ai forming a bore in said shank; (1))" broachinga portion of said bore to across-section conree sponding inshape but slightly smaller: than'saitl. bit; and: (0-) pressing: an end portion. of: said;bi-t; entirely through the broached: portions of; said; bore and; into the.- unbroached: portion: thereof; to enlargesaidibore sufiicientlyvto1hold;the;bit:thererin by.frictionalengagement;

2; Aimethod; of joining a. socketed-shanketoya polygonal; cross-section bitto form an internal wrenching tool,- comprising the, steps of c (a); forming abore insaidshank; (b) breaching. a portion of said bore; to a cross-section corre-v spending in shape but-slightly smaller thanlsaid polygonalbit and (c) forming, an end portionof. said bit with abroaching edge and pressing said, end portion. entirely through ,saidbroached portionof the shank, andseating it into the'un- 4. A methodof joining, a socketed shank to anon" irc'ul a jcros's-sectionbit; to-form an internall wrenching tool; comprising the- Steps of: (a); f' rming a boreiirr said shank; having an opening; in -communicationwith said socket and another opening adapted to-receive'- said bit; (b) performing ian initial broaching operation to-en lclii'ge endportiom of said bore-adjacent said other opening} to-a cross-sectionalshape;- a per-- tion of.whichwapproximates that d'efined by at least-two radiaily extendedp ortion-s of the i crosssectionof" saidbit but radially undersizedwith respect meaty-enormperforming- -a secondary breaching operation-through the'operation -ofthebit itself by forming j' an' end 0e Said: bit with: a broaching edge; and inserting said end in the. initially broached "end oi the-bore and 'pressingrit throughsaid 'initially broached? portion and at least? "part: way into "the unbroached portion whereby 'at leasttwo longitudinally extending. seats are formed in said shank to retain saidlbit byfri-tional engagement 5. A method of joinin-g a sock-et'ed shank-to a, polygonal cross section bit; to for-m aninternal wrenching tool? comprising-the steps ot: (a)

forming a bore in-said slianlij (-Zi) performing mnion-l broaching operat-ion toenlargeoneaend portiorr of said bore to a cross sectional shape apprcrime-ting- 'tl'iatdefined by at least some of: the apices of the cross-section of saidbi-t; but undersized with-respect thereto; and ((2) performing a secondary broacliing operation-by means'of; the -bit-itslf by forming an endofsaid bit" withratflleast' -one' breaching e d ge and inserting said" end? hr theinitially broached 'end of'i' thev bore and pressingit through; said initially.

1 broached portion and at least part w-ayinto the 1 ,430,904 M Carlson se t.'26;.-1922 

